Artifactual FA dimers mimic FAHFA signals in untargeted metabolomics pipelines
FA esters of hydroxy FAs (FAHFAs) are lipokines with extensive structural and regional isomeric diversity that impact multiple physiological functions, including insulin sensitivity and glucose homeostasis. Because of their low molar abundance, FAHFAs are typically quantified using highly sensitive...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2022-05-01
|
| Series: | Journal of Lipid Research |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022227522000347 |
| _version_ | 1817980062678384640 |
|---|---|
| author | Alisa B. Nelson Lisa S. Chow Curtis C. Hughey Peter A. Crawford Patrycja Puchalska |
| author_facet | Alisa B. Nelson Lisa S. Chow Curtis C. Hughey Peter A. Crawford Patrycja Puchalska |
| author_sort | Alisa B. Nelson |
| collection | DOAJ |
| description | FA esters of hydroxy FAs (FAHFAs) are lipokines with extensive structural and regional isomeric diversity that impact multiple physiological functions, including insulin sensitivity and glucose homeostasis. Because of their low molar abundance, FAHFAs are typically quantified using highly sensitive LC-MS/MS methods. Numerous relevant MS databases house in silico-spectra that allow identification and speciation of FAHFAs. These provisional chemical feature assignments provide a useful starting point but could lead to misidentification. To address this possibility, we analyzed human serum with a commonly applied high-resolution LC-MS untargeted metabolomics platform. We found that many chemical features are putatively assigned to the FAHFA lipid class based on exact mass and fragmentation patterns matching spectral databases. Careful validation using authentic standards revealed that many investigated signals provisionally assigned as FAHFAs are in fact FA dimers formed in the LC-MS pipeline. These isobaric FA dimers differ structurally only by the presence of an olefinic bond. Furthermore, stable isotope-labeled oleic acid spiked into human serum at subphysiological concentrations showed concentration-dependent formation of a diverse repertoire of FA dimers that analytically mimicked FAHFAs. Conversely, validated FAHFA species did not form spontaneously in the LC-MS pipeline. Together, these findings underscore that FAHFAs are endogenous lipid species. However, nonbiological FA dimers forming in the setting of high concentrations of FFAs can be misidentified as FAHFAs. Based on these results, we assembled a FA dimer database to identify nonbiological FA dimers in untargeted metabolomics datasets. |
| first_indexed | 2024-04-13T22:48:49Z |
| format | Article |
| id | doaj.art-ea68d57e609a49d9be74eb5769a5bd12 |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-04-13T22:48:49Z |
| publishDate | 2022-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-ea68d57e609a49d9be74eb5769a5bd122022-12-22T02:26:16ZengElsevierJournal of Lipid Research0022-22752022-05-01635100201Artifactual FA dimers mimic FAHFA signals in untargeted metabolomics pipelinesAlisa B. Nelson0Lisa S. Chow1Curtis C. Hughey2Peter A. Crawford3Patrycja Puchalska4Division of Molecular Medicine; Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Bioinformatics and Computational Biology Program, University of Minnesota, Minneapolis, MN, USADivision of Diabetes, Endocrinology and Metabolism; Department of Medicine, University of Minnesota, Minneapolis, MN, USADivision of Molecular Medicine; Department of Medicine, University of Minnesota, Minneapolis, MN, USADivision of Molecular Medicine; Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Bioinformatics and Computational Biology Program, University of Minnesota, Minneapolis, MN, USA; Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA; Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA; For correspondence: Peter A. Crawford; Patrycja PuchalskaDivision of Molecular Medicine; Department of Medicine, University of Minnesota, Minneapolis, MN, USA; For correspondence: Peter A. Crawford; Patrycja PuchalskaFA esters of hydroxy FAs (FAHFAs) are lipokines with extensive structural and regional isomeric diversity that impact multiple physiological functions, including insulin sensitivity and glucose homeostasis. Because of their low molar abundance, FAHFAs are typically quantified using highly sensitive LC-MS/MS methods. Numerous relevant MS databases house in silico-spectra that allow identification and speciation of FAHFAs. These provisional chemical feature assignments provide a useful starting point but could lead to misidentification. To address this possibility, we analyzed human serum with a commonly applied high-resolution LC-MS untargeted metabolomics platform. We found that many chemical features are putatively assigned to the FAHFA lipid class based on exact mass and fragmentation patterns matching spectral databases. Careful validation using authentic standards revealed that many investigated signals provisionally assigned as FAHFAs are in fact FA dimers formed in the LC-MS pipeline. These isobaric FA dimers differ structurally only by the presence of an olefinic bond. Furthermore, stable isotope-labeled oleic acid spiked into human serum at subphysiological concentrations showed concentration-dependent formation of a diverse repertoire of FA dimers that analytically mimicked FAHFAs. Conversely, validated FAHFA species did not form spontaneously in the LC-MS pipeline. Together, these findings underscore that FAHFAs are endogenous lipid species. However, nonbiological FA dimers forming in the setting of high concentrations of FFAs can be misidentified as FAHFAs. Based on these results, we assembled a FA dimer database to identify nonbiological FA dimers in untargeted metabolomics datasets.http://www.sciencedirect.com/science/article/pii/S0022227522000347insulin resistancelipidomicslipidsobesityadipose tissueLC-MS/MS |
| spellingShingle | Alisa B. Nelson Lisa S. Chow Curtis C. Hughey Peter A. Crawford Patrycja Puchalska Artifactual FA dimers mimic FAHFA signals in untargeted metabolomics pipelines Journal of Lipid Research insulin resistance lipidomics lipids obesity adipose tissue LC-MS/MS |
| title | Artifactual FA dimers mimic FAHFA signals in untargeted metabolomics pipelines |
| title_full | Artifactual FA dimers mimic FAHFA signals in untargeted metabolomics pipelines |
| title_fullStr | Artifactual FA dimers mimic FAHFA signals in untargeted metabolomics pipelines |
| title_full_unstemmed | Artifactual FA dimers mimic FAHFA signals in untargeted metabolomics pipelines |
| title_short | Artifactual FA dimers mimic FAHFA signals in untargeted metabolomics pipelines |
| title_sort | artifactual fa dimers mimic fahfa signals in untargeted metabolomics pipelines |
| topic | insulin resistance lipidomics lipids obesity adipose tissue LC-MS/MS |
| url | http://www.sciencedirect.com/science/article/pii/S0022227522000347 |
| work_keys_str_mv | AT alisabnelson artifactualfadimersmimicfahfasignalsinuntargetedmetabolomicspipelines AT lisaschow artifactualfadimersmimicfahfasignalsinuntargetedmetabolomicspipelines AT curtischughey artifactualfadimersmimicfahfasignalsinuntargetedmetabolomicspipelines AT peteracrawford artifactualfadimersmimicfahfasignalsinuntargetedmetabolomicspipelines AT patrycjapuchalska artifactualfadimersmimicfahfasignalsinuntargetedmetabolomicspipelines |